Added browser tests to test the BudgetAPI. Also added BudgetAPI to ExperimentalWebPlatformFeatures.

chrome/test/data/result_queue.js

Index: chrome/test/data/result_queue.js
diff --git a/chrome/test/data/result_queue.js b/chrome/test/data/result_queue.js
new file mode 100644
index 0000000000000000000000000000000000000000..18dc969015402efcd75e31b0eb6354a8d99e4341
--- /dev/null
+++ b/chrome/test/data/result_queue.js
@@ -0,0 +1,52 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Queue storing asynchronous results received from the Service Worker. Results
+// are sent to the test when requested.
+function ResultQueue() {
+  // Invariant: this.queue.length == 0 || this.pendingGets == 0
+  this.queue = [];
+  this.pendingGets = 0;
+}
+
+// Adds a data item to the queue. Will be sent to the test if there are
+// pendingGets.
+ResultQueue.prototype.push = function(data) {
+  if (this.pendingGets > 0) {
+    this.pendingGets--;
+    sendResultToTest(data);
+  } else {
+    this.queue.unshift(data);
+  }
+};
+
+// Called by native. Sends the next data item to the test if it is available.
+// Otherwise increments pendingGets so it will be delivered when received.
+ResultQueue.prototype.pop = function() {
+  if (this.queue.length) {
+    sendResultToTest(this.queue.pop());
+  } else {
+    this.pendingGets++;
+  }
+};
+
+// Called by native. Immediately sends the next data item to the test if it is
+// available, otherwise sends null.
+ResultQueue.prototype.popImmediately = function() {
+  sendResultToTest(this.queue.length ? this.queue.pop() : null);
+};
+
+// Sends data back to the test. This must be in response to an earlier
+// request, but it's ok to respond asynchronously. The request blocks until
+// the response is sent.
+function sendResultToTest(result) {
+  console.log('sendResultToTest: ' + result);
+  if (window.domAutomationController) {
+    domAutomationController.send('' + result);
+  }
+}
+
+function sendErrorToTest(error) {
+  sendResultToTest(error.name + ' - ' + error.message);
+}